1. Field of the Invention
This invention relates to an exhaust emission control device of an internal combustion engine.
2. Description of the Related Art
A three-way catalyst is widely used as the exhaust emission purification catalyst of an internal combustion engine. However, current three-way catalyst has a significantly low efficiency when the temperature is low. For this, various studies are being made to exploit catalysts which are highly active even at low temperatures to thereby decrease emission when the engine starts in low temperature conditions.
U.S. Pat. No. 5,776,417 discloses an exhaust emission control device using a catalyst which is highly active at relatively low temperature.